Offset boring head



Jan. 23, 1968 M. L. BENJAMIN ET AL OFFSET BORING HEAD Filed Nov. 30, 1965 ZNVENTORS M/LT 0/1} L. BENJAMIN [PAW/D D. WALKER Z flL 190/? N. M/L ES WE on? A V1 ORNEYS United States Patent Ofiice 3,354,799 Patented den. 23, 1968 3,364,799 OFFSET BGRING HEAD Milton L. Benjamin, David D. Walker, and Wilbur N. Miles, Chagrin Falls, ()hio, assignors to Erickson Tool Company, Solon, Ghio, a corporation of Ghio Filed Nov. 30, 1965, Ser. No. 519,538 19 Claims. (Ci. 7758) ABSTRACT OF THE DISCLOSURE An adjustable boring head having a tool mounting slide movable lengthwise in a slideway, and releasable locking means for drawing the tool mounting slide against the slideway thereby to frictionally lock the tool mounting slide in adjusted position.

This invention relates to a precision offset boring head by which tool settings may be made and maintained with great accuracy.

It is a primary object of this invention to provide a novel locking assembly for locking the tool mounting slide and its adjusting dial in precise adjusted position.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

FIG. 1 is a side elevation view of an offset boring head according to the present invention;

FIG. 2 is an end elevation view as viewed from the left-hand side of FIG. 1;

FIG, 3 is a cross-section view taken substantially along the line 33, FIG. 1;

FIG. 4 is a cross-section view taken substantially along the line 44, FIG. 2;

FIG. 5 is a cross-section view taken substantially along the line 5-5, FIG. 4;

FIG. 6 is a cross-section view taken substantially along the line 66, FIG. 3;

FIG. 7 is a cross-section View taken substantially along the line 77, FIG. 4;

FIG. 8 is a fragmentary crosssection view on enlarged scale taken substantially along the line 88, FIG. 6; and

FIG. 9 is an end elevation view of the main body by itself as viewed from the left-hand side of FIG. 4.

Referring now in detail to the drawings, the offset boring head 1 herein comprises a main body or housing 2 having a central internally threaded bore 3 for mounting on a shank or the like (not shown) through which the offset boring head 1 is adapted to be mounted in a spindle or similar part of a machine tool for rotation thereby.

A tool holding slide 4 is mounted for adjustment within the body 2 as hereinafter described in detail, and is formed with cross bores 5 and 6 for receiving the shank of a cutting tool (not shown) either in axially disposed position in bore '5, or radially disposed position in bore 6, such tool being locked in either bore by the setscrew 7.

An adjusting dial 3 is rotatably mounted on the body 2 and has indicia cooperating with Vernier indicia on the adjacent portion of body 2, rotation of the dial 8 thus effecting precision radial adjustment of the tool holding slide 4. Said dial 8 is held against axial movement on 'body 2 by means of the cap 9 which is mounted on the latter by screws 10.

A thumb screw 11 which forms part of a locking mechanism extends outwardly from the body 2 for locking the slide 4 and dial *3 in adjusted position. As will be seen, rotation of the dial 8 will vary the radial distance between the axes of bores 3 and 5, whereby a cutting tool in said bore 5 (or in the other bore 6) may be precisely radially adjusted to permit holes of varying sizes to be accurately bored in a workpiece.

Referring now to the internal construction of the offset boring head 1, the portion of the body 2 on which the dial 8 rotates has perpendicular diametrical slots 12 and 14 to axially guide the adjusting bar 15 which has its ends in threaded engagement with said dial 8 as best shown in FIG. 5, and to receive for radial movement the flatted extension 16 of the slide 4, the slot -14 being enlarged in width to define with cap 9 a slideway 17. The extension 16 has an obliquely disposed cam slot 18, and, as evident from FIG. 4, when the bar 15 is moved toward the right in the slot 12, it will, in engaging the cam slot 18, cause downward radial movement of the slide 4, thus shifting the axis of the bore 5' with respect to the axis of the threaded bore 3 in the body 2. The opening 19 through the cap 9 is elongated as shown in FIGS. 2 and 4 to permit radial movement of the slide 4 in response to rotation of the dial 8.

The locking assembly previously referred to as being operated by thumb screw 11 comprises a pair of axially movable locking pins 2i) which are hooked over (see FIG. 8) the opposite edges of the flanges 21 of the slide and springs 23 in said pins 24 are operative to yieldably hold the flanges 21 against the bottom surfaces 24 of the slideway 17, so that under the infience of axial thrust loads on a cutting tool mounted in the slide 4 there is no movement which would disturb its precise setting. The other ends of the locking pins 2%) are notched to provide beveled cam surfaces 25 engaged by transverse cam pins 26, the latter being actuated by turning the thumb screw 11, there being a force transmission member 27 (such as a Woodruif key) between the end of the thumb screw 11 and the ends of the cam pins 26 as shown in FIGS. 3 and 6. it can be seen that when the cam pins 25 are actuated toward the respective locking pins 29 the latter will be drawn axially so that the hooked ends thereof will tightly press the flanges 21 of the slide 4 against the surfaces 24 of the sl-ideway thus to firmly lock the slide 4 in its adjusted position.

An additional locking feature that is operated at the same time that the locking pins 21 are moved to locking position is the split ring 28 disposed within a counterbore at the end of the dial 8. The thumb screw 11 is threaded in a bushing 29 which is held against rotation in the body by a pair of pins 30 engaged in opposite grooves in said bushing 29. However, the holes in the body 2 in which the pins 3d are disposed are elongated in a direction such that as the cam pins 2e are being urged to locking position, the reaction forces tend to force the bushing 2-9 outwardly of the body 2 and thus the grooves in the bushing 29 act as cam surfaces to spread the pins 34 apart. The inner ends of said pins 3% are engaged with the ends of a split dial locking ring 23 and thus when the thumb screw 11 is tightened, the dial locking ring 28 is expanded in diameter to frictionally engage within the dial 8. Accordingly, the turning of the thumb screw 11 to locking position not only actuates the locking pins Ztl, but, in addition, expands the dial locking ring 28 thus to lock both the slide 4 and the dial 9 in the precise adjusted positions.

In the use of this offset boring head, when it is desired to adjust the radial position of the slide 4, the thumb screw 11 will be loosened slightly to free the slide 4 for adjustment and the dial 8 for turning so that when the dial 8 is turned in either direction the bar 15 having threaded engagement with the dial will be caused to move axially in slot 12 and such movement will, through cam slot 18 of slide 4, eiiect radial adjustment of the latter along slideway 17. When the desired adjustment has been made, the retightening of the thumb screw 11 will lock the slide 4 and dial 8 in such adjusted position.

By employing a cylindrical dial calibrated in thousandths of an inch, accuracy of adjustment by reason of the Vernier scale may be within 0.0001 inch. For example, when the threads in the dial 8 are of 20 pitch, one revolution of the dial 8 will advance the bar 15 0.050 inch in an axial direction and when the angle of the cam slot 18 is 26-34, the slide 4 will move radially 0.025 inch per revolution of the dial 8. Accordingly, O divisions around the dial 8 will indicate .050" change in diameter or 0.001 inch per division and the Vernier scale on the body 2 will enable reading a change in diameter in 0.0001 inch increments.

It will accordingly be seen that the present invention provides an offset boring head l which is compact and highly simplified in construction, and which is capable of achieving and maintaining highly precise adjustment.

Other modes of applying the principle of the invention may be employed, change being made as regards the d tails described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

We therefore particularly point out and distinctly claim as our invention:

1. An adjustable boring head comprising a body having a transverse slideway; a tool mounting slide movable lengthwise in said slideway; dial means rotatable on said body and operatively connected to said slide to adjustably position the latter in said slideway responsive to rotation of said dial means; and releasable locking means in said body engaged with said slide for drawing said slide against said slideway thereby to frict-ionally lock said slide in adjusted position with respect to said body.

2. The adjustable boring head of claim 1 wherein spring means associated with said locking means is eftective to yieldably retain said slide against said slideway when said locking means is released for adjustment of said slide.

3. The adjustable boring head of claim 1 wherein said releasable locking means comprises at least one pin member axially movable in said body and having a portion transversely overlapped with said slide, and pin actuating means for moving said pin so as to draw said slide against said slideway.

4. The adjustable boring head of claim ll wherein said slide has a flange over which said one pin member is hooked to provide such transversely overlapped portion.

'5. The adjustable boring head of claim 1 wherein there are a pair of axially movable pin members in said body having a portion transversely overlapped with said slide, and and said pin actuating means includes a pair of transverse cam pins, said pin members having beveled cam surfaces engaged by said cam pins, and means for actuating said cam pins toward said pin members to draw said pin members in a direction urging said slide against said slideway.

5. The adjustable boring head of claim 5 wherein said last-mentioned means comprises a thumb screw which when tightened urges a force transmission member against the outer ends of said cam pins.

7. An adjustable boring head comprising a body having a transverse slideway; a tool mounting slide movable lengthwise in said slideway; dial means rotatable on said body and operatively connected to said slide to adjustably position the latter in said slideway responsive to rotation of said dial means; an expansible ring non-rotatably mounted in said body and disposed within said dial means; and means for expanding said ring into engagement with said dial means thereby to frictionally lock said dial means at the desired adjusted position.

8. The adjustable boring head of claim 7 wherein said means for expanding said rin into engagement with said dial means comprises a thumb screw, a bushing in an opening in said body in which said thumb screw is threaded, a pair of pin means engaged in opposite grooves in said bushing for holding said bushing against rotation in said body, the inner ends of said pin means engaging the ends of said locking ring, said thumb screw, when tightened, forcing said bushing out of said body to cause said grooves in said bushing to act as cam surfaces to spread said pin means apart for expanding said locking ring.

9. An adjustable boring head comprising a body having a transverse slideway; a tool mounting slide movable lengthwise in said slideway; dial means rotatable on said body and operatively connected to said slide to adjustably position the latter in said slideway responsive to rotation of said dial means; and releasable locking means in said body engaged with said slide for drawing said slide against said slideway thereby to frictionally lock said slide in adjusted position with respect to said body, said locking means further including an expansible ring nonrotatably mounted in said body and disposed within said dial means, and means for expanding said ring into engagement with said dial means thereby to frictionally lock said dial means at the desired adjusted position of said slide.

10. The adjustable boring head of claim 9 wherein said releasable locking means comprises at least one pin member axially movable in said 'body and having a portion transversely overlapped with said slide, and pin actuating means including a thumb screw for moving said pin member so as to draw said slide against said slideway; and means for expanding said ring into engagement with said dial means comprising a bushing in which said thumb screw is threaded, and a pair of additional pins engaged in opposite grooves in said bushing for holding said bushing against rotation in said body, the inner ends of said additional pins engaging the ends of said locking ring, whereby tightening of said thumb screw tends to force said bushing outwardly of said body during which said grooves in said bushing act as cam surfaces to spread said additional pins apart for expanding said locking ring.

References Cited UNlTED STATES PATENTS 3,159,060 12/1964- Miles 7758 GERALD A. DOST, Primary Examiner, 

